Chlorite of hydrothermal origin formed in the Strzelin and Borów granites (Fore-Sudetic Block, Poland)

Abstract

Chlorite, a prod uct of very low-to low-grade meta mor phism, is fre quently used as a geothermometer be cause of the fact that its struc ture and chem i cal com po si tion can re flect the phys i cal and chem i cal con di tions of its for ma tion. In the hy dro ther mally al tered Strzelin and Borów gran ites (the Fore-Sudetic Block, Po land) chlorite is ubiq ui tous. It is found in two forms: spherulitic and post-bi o tite, and was formed in dif fer ent ways in dif fer ent parts of the Strzelin and Borów gran ites: as re sult of (1) re place ment of bi o tite or (2) crystallisation from fluid. The chlorite formed in the Borów gran ite shows a higher Fe con tent than that in the Strzelin gran ite, a fea ture re lated to the con tent of Mg and Fe in the host rock. Tem per a tures of chlorite for ma tion are the low est for un al tered gran ite and then grad u ally in crease for slightly, mod er ately and strongly al tered gran ite and are the high est in hy dro ther mal veins. This means that the tem per a ture of the hydro ther mal fluid was higher than that of the al tered gra nitic bod ies. More over, the spherulitic chlorite formed at a higher tem per a ture than did the post-bi o tite chlorite, and is usu ally smaller be cause bi o tite re place ment lasted lon ger than did the crystallisation of spherulitic chlorite di rectly from hy dro ther mal fluid. Such pat terns are likely to oc cur in other gra nitic bod ies.

Múltiplos estágios de alteração hidrotermal do depósito de óxido de ferro-cobre-ouro Furnas, Província Carajás: evolução paragenética e química mineral.

“…Composições recalculadas através do software Mica+ (Yavuz, 2003 a,b (Yavuz et. al, 2015) Amostra 56 Lito (Ciesielczuk, 2012), demonstrando a separação da clorita em três grupos principais.…”